Unravelling the Mechanism of the Ru/C‐Catalysed Isohexide and Ether Isomerization by Hydrogen Isotope Exchange

In this article we show that the catalytic isomerization of isohexide sugar alcohols as well as their respective ethers can occur by a hydride-based mechanism rather than a dehydrogenation/re-hydrogenation. C−H bonds in α-position to hydroxy and ether groups are activated using Ru/C as solid catalyst at temperatures as high as 160 °C and above. Hydrogen isotope exchange experiments proved that a full hydride exchange and isomerization is possible for isohexides but unexpectedly also for their methyl ethers. This is of great importance as it proves the co-existence of the both mechanisms for reactions that were so far assumed to occur solely by a dehydrogenation/re-hydrogenation. Hence, this co-existence should be taken into account for kinetic investigations of such reaction systems especially in the conversion of biomass-based chemicals under hydrogenation conditions

Untying a nanoscale knotted polymer structure to linear chains for efficient gene delivery in vitro and to the brain

The purpose of this study was to develop a platform transfection technology, for applications in the brain, which could transfect astrocytes without requiring cell specific functionalization and without the common cause of toxicity through high charge density. Here we show that a simple and scalable preparation technique can be used to produce a “knot” structured cationic polymer, where single growing chains can crosslink together via disulphide intramolecular crosslinks (internal cyclizations). This well-defined knot structure can thus “untie” under reducing conditions, showing a more favorable transfection profile for astrocytes compared to 25 kDa-PEI (48-fold), SuperFect® (39-fold) and Lipofectamine®2000 (18-fold) whilst maintaining neural cell viability at over 80% after four days of culture. The high transfection/lack of toxicity of this knot structured polymer in vitro, combined with its ability to mediate luciferase transgene expression in the adult rat brain, demonstrates its use as a platform transfection technology which should be investigated further for neurodegenerative disease therapies

Physical activity attitudes, intentions and behaviour among 18-25 year olds: a mixed method study

Peer reviewedPublisher PD

Analysis of the global atmospheric background sulfur budget in a multi-model framework

Sulfate aerosol in the stratosphere is an important climate driver, causing solar dimming in the years after major volcanic eruptions. Hence, a growing number of general circulation models are adapting interactive sulfur and aerosol schemes to improve the representation of relevant chemical processes and associated feedbacks. However, uncertainties of these schemes are not well constrained. Stratospheric sulfate is modulated by natural emissions of sulfur-containing species, including volcanic eruptive, and anthropogenic emissions. Model intercomparisons have examined the effects of volcanic eruptions, whereas the background conditions of the sulfur cycle have not been addressed in a global model intercomparison project. Assessing background conditions in global models allows us to identify model discrepancies as they are masked by large perturbations such as volcanic eruptions, yet may still matter in the aftermath of such a disturbance. Here, we analyze the atmospheric burden, seasonal cycle, and vertical and meridional distribution of the main sulfur species among nine global atmospheric aerosol models that are widely used in the stratospheric aerosol research community. We use observational and reanalysis data to evaluate model results. Overall, models agree that the three dominant sulfur species in terms of burdens (sulfate aerosol, OCS, and SO2) make up about 98 % of stratospheric sulfur and 95 % of tropospheric sulfur. However, models vary considerably in the partitioning between these species. Models agree that anthropogenic emission of SO2 strongly affects the sulfate aerosol burden in the Northern Hemispheric troposphere, while its importance is very uncertain in other regions. The total deposition of sulfur varies among models, deviating by a factor of two, but models agree that sulfate aerosol is the main form in which sulfur is deposited. Additionally, the partitioning between wet and dry deposition fluxes is highly model dependent. We investigate the areas of greatest variability in the sulfur species burdens and find that inter-model variability is low in the tropics and increases towards the poles. Seasonality in the southern hemisphere is depicted very similar among models. Differences are largest in the dynamically active northern hemispheric extratropical region, hence some of the differences could be attributed to the differences in the representation of the stratospheric circulation among underlying general circulation models. This study highlights that the differences in the atmospheric sulfur budget among the models arise from the representation of both chemical and dynamical processes, whose interplay complicates the bias attribution. Several problematic points identified for individual models are related to the specifics of the chemistry schemes, model resolution, and representation of cross-tropopause transport in the extratropics. Further model intercomparison research is needed focusing on the clarification of the reasons for biases, given also the importance of this topic for the stratospheric aerosol injection studies.</p

Are skin disorders related to work strain in hospital workers? A cross-sectional study

To evaluate whether occupational stress factors (high demands, low control, low social support, strain, and iso-strain) are associated with skin disorders in hospital workers and whether psychological problems, such as anxiety and depression, act as potential mechanisms through which occupational stress factors are associated with skin disorders

Factors accounting for the association between anxiety and depression, and eczema: the Hordaland health study (HUSK)

<p>Abstract</p> <p>Background</p> <p>The association between anxiety and depression, and eczema is well known in the literature, but factors underlying this association remain unclear. Low levels of omega-3 fatty acids and female gender have been found to be associated with both depression and eczema. Somatization and health anxiety are known to be associated with anxiety and depression, further, somatization symptoms and health anxiety have also been found in several dermatological conditions. Accordingly, omega-3 fatty acid supplement, female gender, somatization and health anxiety are possible contributing factors in the association between anxiety and depression, and eczema. The aim of the study is to examine the relevance of proposed contributing factors for the association between anxiety and depression, and eczema, including, omega-3 fatty acid supplement, female gender, health anxiety and somatization.</p> <p>Methods</p> <p>Anxiety and depression was measured in the general population (n = 15715) employing the Hospital Anxiety and Depression Scale (HADS). Information on eczema, female gender, omega-3 fatty acid supplement, health anxiety and somatization was obtained by self-report.</p> <p>Results</p> <p>Somatization and health anxiety accounted for more than half of the association between anxiety/depression, and eczema, while the other factors examined were of minor relevance for the association of interest.</p> <p>Conclusions</p> <p>We found no support for female gender and omega-3 fatty acid supplement as contributing factors in the association between anxiety/depression, and eczema. Somatization and health anxiety accounted for about half of the association between anxiety/depression, and eczema, somatization contributed most. The association between anxiety/depression, and eczema was insignificant after adjustment for somatization and health anxiety. Biological mechanisms underlying the mediating effect of somatization are yet to be revealed.</p

Using Polarized Spectroscopy to Investigate Order in Thin-Films of Ionic Self-Assembled Materials Based on Azo-Dyes

Three series of ionic self-assembled materials based on anionic azo-dyes and cationic benzalkonium surfactants were synthesized and thin films were prepared by spin-casting. These thin films appear isotropic when investigated with polarized optical microscopy, although they are highly anisotropic. Here, three series of homologous materials were studied to rationalize this observation. Investigating thin films of ordered molecular materials relies to a large extent on advanced experimental methods and large research infrastructure. A statement that in particular is true for thin films with nanoscopic order, where X-ray reflectometry, X-ray and neutron scattering, electron microscopy and atom force microscopy (AFM) has to be used to elucidate film morphology and the underlying molecular structure. Here, the thin films were investigated using AFM, optical microscopy and polarized absorption spectroscopy. It was shown that by using numerical method for treating the polarized absorption spectroscopy data, the molecular structure can be elucidated. Further, it was shown that polarized optical spectroscopy is a general tool that allows determination of the molecular order in thin films. Finally, it was found that full control of thermal history and rigorous control of the ionic self-assembly conditions are required to reproducibly make these materials of high nanoscopic order. Similarly, the conditions for spin-casting are shown to be determining for the overall thin film morphology, while molecular order is maintained

DESIGN OF GEODETIC NETWORKS BASED ON OUTLIER IDENTIFICATION CRITERIA: AN EXAMPLE APPLIED TO THE LEVELING NETWORK

We present a numerical simulation method for designing geodetic networks. The quality criterion considered is based on the power of the test of data snooping testing procedure. This criterion expresses the probability of the data snooping to identify correctly an outlier. In general, the power of the test is defined theoretically. However, with the advent of the fast computers and large data storage systems, it can be estimated using numerical simulation. Here, the number of experiments in which the data snooping procedure identifies the outlier correctly is counted using Monte Carlos simulations. If the network configuration does not meet the reliability criterion at some part, then it can be improved by adding required observation to the surveying plan. The method does not use real observations. Thus, it depends on the geometrical configuration of the network; the uncertainty of the observations; and the size of outlier. The proposed method is demonstrated by practical application of one simulated leveling network. Results showed the needs of five additional observations between adjacent stations. The addition of these new observations improved the internal reliability of approximately 18%. Therefore, the final designed network must be able to identify and resist against the undetectable outliers – according to the probability levels